[mkgmap-dev] mkgmap ToDo list

Thu Apr 17 06:54:39 BST 2014

I currently have basically no time - so I'm just reading on the list in 
skip through mode. Unable to test - but I'm pretty sure there is a big 
bug related to the oneway handling and reversing of ways. I'm also quite 
sure it wasn't there last year and got introduced with the change of the 
style-file getting all tags instead of internal handling.

My style is a big mess right now (trying to adapt to the changes needed, 
but fucking up because no set mkgmap:access=yes/no and delete 
mkgmap:access shortcut exists anymore amongst other imcompatibilities 
compared to before) -  but I'm pretty sure that the oneway handling - 
also related to oneway=yes or oneway=-1 set in the lines file somehow 
doesn't work correctly.

I often reverse ways - in order to have depending on direction different 
classification of the way (regarding both layout and routing priority) 
and have noticed that lately I'm routed against the intended direction 
because mkgmap puts the way in the wrong direction. And I'm 95% sure 
that the error is on mkgmap not the style-file but didn't find the time 
to analyze...

Being in China right now behind the great firewall - it's also 
cumbersome to access my SVN and other things as they are blocked - I 
won't be able to help much/at all before mid June in finding or 
specifying bugs...

Alternative 1 sounds best - as it would be in line with the old 
behaviour if I'm not incorrectly understanding it here...
Or Alternative 3 - don't do anything!! Leave it to the style developer - 
wasn't this the old behaviour?
I don't know since when this is bugged - but I'm sure 1 year ago 
everything worked correctly if you assigned all ways to either 
oneway=yes or oneway=-1 (or was it reverse?). Only thing to normalize 
was true or 1 to yes and so on...

On 17.04.2014 13:42, Gerd Petermann wrote:
> Hi Henning,
>
> okay. I think WanMil told me that before, but I forgot again ...
>
> A few details:
>
> mkgmap always reversed routable ways with oneway=-1 or oneway=reverse 
> after style processing.
>
> With r2944 I've changed the code so that this happens before calling 
> RoadMerger and also that overlaying
> lines are reversed.
>
> If I got that right, the style may use different types for overlaying 
> lines, depending on the oneway tag,
> so if you use the same style for r2943 or older and for current 
> version, you should see a difference
> for oneway=-1 ways.
> I don't know how difficult it is to change the style to produce 
> correct results with current version again,
> but you have to remember that the way is reversed, so left will be 
> right, forward will be backward.
>
> I see two alternatives:
> 1) mkgmap reverses the way before style processing. This requires also 
> to reverse all tags like
> bicycle:left, car:forward etc, so it is not trivial. On the other 
> hand, it might allow to merge more
> roads in RoadMerger.
> 2) mkgmap makes sure that overlaying lines are NOT reversed. I think 
> this can be done
> with the attached patch.
>
> By the way:  There are also tags on nodes which depend on the 
> direction of the way, see
> http://gis.19327.n5.nabble.com/direction-forward-backward-on-nodes-tt5803072.html
>
> I think we can ignore this because in the points file you can't detect 
> the direction of the way.
>
> Gerd
> ------------------------------------------------------------------------
> Date: Wed, 16 Apr 2014 23:00:35 +0200
> From: osm at aighes.de
> To: mkgmap-dev at lists.mkgmap.org.uk
> Subject: Re: [mkgmap-dev] mkgmap ToDo list
>
> Am 16.04.2014 22:01, schrieb GerdP:
>
>     Why do you think that it is a bug?
>
> Think about oneway=-1 and in style you add oneway-arrows (link mapnik 
> does). In style you will handle -1 special, because arrows should 
> drawn in oposite direction of way. If mkgmap now changes direction of 
> the way, arrows should be in wrong direction, or am I wrong?
>
> Henning
>
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